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Abubakar Fuad Abubakar,Huanling Wang,Yizhe Wu 대한토목학회 2024 KSCE Journal of Civil Engineering Vol.28 No.6
Uniaxial/triaxial compression and scanning/backscattered electron microscopy (SEM/BSEM) tests have been conducted in this study to explore the hydro-mechanical (H-M) response and failure mechanism of basalt from Baihetan hydropower station in China. The experimental findings show that the characteristic strengths, deformation behavior, and failure modes of basalt are greatly influenced by confining and pore pressures. Observations from SEM/BSEM tests reveal that the failure mode is due to the development and growth of intergranular/transgranular microcracks. Under H-M loading conditions, the permeability evolution of basalt exhibits nonlinear and distinct characteristics. Additionally, the permeability evolution and failure mode of basalt under the influence of both confining and pore pressures have been discussed. To further describe the H-M response of rocks under loading, continuum damage mechanics theory, in conjunction with strain equivalence and effective stress principles, has been used to establish an entropy distribution-based probabilistic damage constitutive model. To validate the model, the theoretical results have been compared with those obtained from experiments for basalt and other quasi-brittle rock-like materials. The outcome of this study has implications for the engineering design and safety evaluation for structures that lie within rock masses vulnerable to H-M coupling disasters.
Abubakar Adamu,Jitsupa Deepho,Abdulkarim Hassan Ibrahim,Auwal Bala Abubakar 경남대학교 수학교육과 2021 Nonlinear Functional Analysis and Applications Vol.26 No.2
In this paper, an inertial Halpern-type forward backward iterative algorithm for approximating solution of a monotone inclusion problem whose solution is also a fixed point of some nonlinear mapping is introduced and studied. Strong convergence theorem is established in a real Hilbert space. Furthermore, our theorem is applied to variational inequality problems, convex minimization problems and image restoration problems. Finally, numerical illustrations are presented to support the main theorem and its applications.
Abubakar Abdussamad,Manogaran Motharasan,Yasid Nur Adeela,Othman Ahmad Razi,Shukor Mohd Yunus Abd 한국화학공학회 2023 Korean Journal of Chemical Engineering Vol.40 No.8
More concerning about dye pollution is that it is being worsened by a lack of adequate treatment. This study optimized the adsorption of Trypan Blue (TB) dye in an aqueous solution using screened bacterial biomass. Among twelve different bacterial isolates screened against TB dye, Pseudomonas sp. strain MM02 showed a high adsorption percentage of 36.5%. The adsorption process was enhanced using one-factor-at-a-time (OFAT) and response surface methodology (RSM) optimization. An adsorption of 59% was achieved through OFAT optimization (TB dye concentration 15 ppm, contact time 20 min, pH 6.5, agitation speed 150 rpm, adsorbent amount 1.10 g and temperature 30 °C), while statistical optimization using RSM resulted in a further increased adsorption of the dye to 61.51% (TB dye concentration 22.27 ppm, adsorbent size 0.32 g, and temperature 34.27 °C). The results of this investigation demonstrated that OFAT and RSM optimization were effective and that they were also appropriate strategies for optimizing the adsorption of TB dye by Pseudomonas sp. strain MM02. Thus, it is possible to achieve the necessary water quality while saving money by using the strain MM02 of Pseudomonas sp. MM02 in a water treatment facility. Changes in free energy of adsorption (ΔGo), enthalpy (ΔHo) and entropy (ΔSo) as well as the activation energy (Ea) were determined. ΔHo, ΔSo and Ea with pH control were −26.5, −230 and 43.5 kJ/mol. The result showed that bacterial cellulose could be employed as an effective sorbent for the removal of direct dye from an aqueous solution and the values of ΔHo, ΔGo and Ea indicate that the adsorption of direct dye onto bacterial cellulose was a physisorption process: ΔGo and ΔHo.
Skilled Migration, Human Capital and Educated Unemployment
( Abubakar Lawan Ngoma ),( Usman Umaru Bubaram ) 한양대학교 경제연구소 2021 JOURNAL OF ECONOMIC RESEARCH Vol.26 No.3
It is, theoretically, argued that the possibility of migration to where-the-returns to education is higher promotes human capital investment and educated unemployment in the migrants’ source countries. However, empirical studies seeking to support this claim are uncommon in the received literature. This paper examines the effect of skilled migration on human capital formation and unemployment of educated workers in migrants’ source developing countries. The paper uses System Generalised Method of Moments (SGMM) technique on panel dataset from 96 migrant-sending countries over the period of 1980 - 2000. The results reveal that skilled migration exerts positive effect on educational investment in migrants’ source countries. The results further show that the possibility of skilled migration attenuates skilled unemployment in migrants’ source countries. From the policy standpoint, the paper shows that policymakers in migrantsending countries can use the potentials of international migration to boost their countries level of human capital and reduce skilled unemployment.